The decomposition of the Ethiopian Kenticha tantalite ore was studied using the KOH fusion and H2O leaching system at 400 0C for a 1 h reaction time. The experimental results obtained showed that 27 wt% of Ta2O5 was mainly transformed into insoluble KTaO3، not to be KNbO3، and as well، into the dissolved liquor containing 94.73 vol% of Nb2O5 and 75.80 vol% of Ta2O5. The observations، supported by the EDXRF، XRD، and ICP-OES techniques، showed that the ratio of the dissolved mixture of Nb and Ta metal ions was beneficial to the solvent extraction from both Ta2O5 and Nb2O5. Niobium and tantalum were extracted from their neutralized alkaline dissolved and hydrolyzed solution by a new process using the EMIC/AlCl3 ionic liquid as the extractant using selective stripping، precipitation، and calcination of a highly crystalline pure 99.84 wt% of Nb2O5 and amophours 90.81 wt% of Ta2O5. The compositions of the dissolved metal ions and solids were analyzed by the ICP-OES، EDXRF، XRD، and FT-IR techniques.

Keywords: Decomposition, Ionic Liquid, Kenticha Tantalite Ore Mine

Assessment of radioactive contamination in water bodies around mine workings using radiation counterA.O. Owolabi *Pages 795-806Abstract Full Text [PDF 1554KB]

The vulnerability of water bodies to contamination within the neighbourhood of open mine cast environ cannot be overemphasized. Evidence of radioactive trace elements associated with the target minerals in the Plateau State (Nigeria) showed the extent of this vulnerability. In order to address this challenge، the radioactivity levels of water samples from mine ponds، streams، wells، and boreholes around mine sites in the Plateau State were assessed. The water samples were analysed for gross alpha and beta radiation activities using MPC 2000 radiation counter in accordance with the provisions of International Atomic Energy Agency (IAEA) at the Centre for Energy Research and Training (CERT) Zaria. The mean alpha radiation activity dose for the water samples collected from mine ponds، streams، wells، and boreholes was 0.63 + 0.1 Bq/l، 0.13 + 0.1 Bq/l، 0.34 + 0.1 Bq/l، and 0.51 + 0.2 Bq/l، respectively. The mean beta radiation activity dose for the water samples collected from mine ponds، streams، wells and boreholes was 4.1 + 1.8 Bq/l، 1.0 + 0.7Bq/l، 2.4 + 1.9 Bq/l، and 2.7 + 1.3 Bq/l، respectively. The water bodies were unwholesome for human consumption. The present use of water from the mine ponds for irrigation should be discontinued. The specific activities of alpha and beta radiations in the water samples decreased as distance from the mine increased. It is، therefore، clear that the mine sites were the sources of the high radiation values recorded in the water sources.

Flotation process in mechanical cells is carried out in highly turbulent conditions. In this work، the impact of impeller speed on four characteristics of the quiescent zone، i.e. zone height، turbulence، solid percentage، and gas holdup، and their relationship with the entrainment is investigated، and it is shown why at a higher impeller speed، entrainment is not significant. The height of the quiescent zone and its turbulence are measured using a piezoelectric sensor، while an electrical conductivity sensor measures the gas hold-up. A peristaltic pump is applied to take samples from the pulp to measure the solid percentage. The results obtained showed that with increase in the impeller speed from 750 to 1100 rpm، the entrainment value changed from 2.01% to 5.69%. However، the variations in entrainment were not significant at speeds higher than 1100 rpm. It was found that the height of the quiescent zone was independent from the impeller speed، while raising the impeller speed، as long as the solid percentage، turbulence، and gas hold-up are increased، caused a drastic increase in entrainment. Despite the increase in the solid percentage and turbulence، the gas hold-up decreased at impeller speeds higher than 1100 rpm due to the variation in the bubble distribution pattern، so the entrainment raised with a smaller slope. Finally، a model is presented for the entrainment as a function of the three correlated variables using the Ridge regression. The entrainment is then correlated to the impeller speed، explaining the contradictory results from the literature on the effect of impeller speed on the entrainment.

A complete and accurate analysis of the complex spatial structure of heterogeneous hydrocarbon reservoirs requires detailed geological models، i.e. fine resolution models. Due to the high computational cost of simulating such models، single resolution up-scaling techniques are commonly used to reduce the volume of the simulated models at the expense of losing the precision. Several multi-scale techniques have also been developed for simulating heterogeneous reservoirs including those in which a limited number of blocks down-scale، i.e. splitting coarse blocks into fine cells around the well-zones in the case of simulation of hydraulic fracturing. In these cases، locally computed basis functions are employed to construct a global solver at a coarse-scale such as wavelet- and kernel-based up-scaling techniques. In this paper، a novel/robust 2D block-ordering system is presented، which enables solving multi-resolution up-scaling fluid flow simulations. The results will be described for a simple model، and fluid flow equations will be developed in order to show the structure of transmissibility matrix. It is confirmed that with a developed block-ordering system not only the accuracy of history match increases but also the CPU time decreases.

The utilization of the lining type in pressure tunnels is highly dependent on the geological and hydraulic conditions. There are two types of lining، namely concrete and steel lining but steel lining is one of the most expensive arrangements. To decrease the length of steel lining in these tunnels، the concrete lining، which prevents water seepage from the surrounding rock mass، is the appropriate alternative. In this work، a special attention is devoted to limit water losses in the concrete lining of pressure tunnel based on the critical reinforcing ratio in concrete lining. In order to evaluate the effect of internal water pressure on the permeability coefficient variation of the concrete lining and the surrounding rock mass، some simulations of reinforced concrete lining is implemented in the ABAQUS finite element software based on the coupled pore fluid-stress analysis. The results obtained indicate that although the critical reinforcing ratio has an important role in capturing the seepage flows and water losses، it is not sufficient to rely only on this parameter. However، among the various influential factors involved، a suitable arrangement of the reinforcement in the concrete lining should also be considered.

An accurate reservoir characterization is a crucial task for the development of quantitative geological models and reservoir simulation. In the present research work، a novel view is presented on the reservoir characterization using the advantages of thin section image analysis and intelligent classification algorithms. The proposed methodology comprises three main steps. First، four classes of reservoir intervals are defined using a limited number of porosity and permeability values obtained from the core plugs of Kangan and Dalan formations. Then seven micro-scale features including distribution of pore types (interparticle، interaparticle، moldic، and vuggy)، pore complexity، and cement distribution as well as textural characteristics are extracted from thin section images. Finally، the features extracted from each photomicrograph and its corresponding reservoir class are used as the training data for several intelligent classifiers including decision trees، discriminant analysis functions، support vector machines، K-nearest neighbor models and two ensemble algorithms، named bagging and boosting. The relationship between the micro-scale features and the reservoir classes was studied. Performance of all classifiers is evaluated using the concepts of accuracy، precision، recall، and harmonic average. The results obtained showed that the bagging decision tree delivered the best performance among the models and improved the accuracy of simple models up to 7.7% compared with the best single classifier.

Madan Bozorg is an active copper mine located in NE Iran، which is a part of the very wide copper mineralization zone named Miami-Sabzevar copper belt. The main goal of this research work is the 3D model construction of the induced polarization (IP) and resistivity (Rs) data with quantifying the uncertainties using geostatistical methods and drilling. Four profiles were designed and surveyed using the CRSP array based on the boreholes. The data obtained was processed، 2D sections of IP and Rs were prepared for each profile by inverting the data، and these sections were evaluated by some exploratory boreholes in the studied area. Based on the geostatistical methods، 3D block models were constructed for the 2D IP and Rs data، and the uncertainties in the prepared models were obtained. The mineralization location was determined according to the geophysical detected anomalies. In order to check the models، some locations were proposed for drilling in the cases that the borehole data was unavailable. The drilling results indicated a high correlation between the identified anomalies from the models and mineralization in the boreholes. The results obtained show that it is possible to construct 3D models from surveyed 2D IP & Rs data with an acceptable error level. In this way، the suggested omitted drilling locations were optimized so that more potentials could be obtained for copper exploration by the least number of boreholes.

Production planning in mineral exploitation should be undertaken to maximize exploited ore at a minimum unplanned dilution. Unplanned dilution reduction is among the ways to enhance the quality of products، and hence، reduce the associated costs، resulting in a higher profit. In this way، firstly، all the parameters contributing to unplanned dilution in underground stopes and specifically the cut-and-fill stoping method are identified. Secondly، the parameters are weighed using the fuzzy-Delphi analytical hierarchy process. Thirdly، the most effective parameters are selected among the pool of effective parameters. Finally، in order to present a novel classification system for an unplanned dilution assessment، a new index called stope unplanned dilution index (SUDI) is introduced. SUDI represents the extent to which a cut-and-fill stope is susceptible to unplanned dilution. That is، having the value of this index، one may classify the cut-and-fill stopes into five groups according to robustness versus unplanned dilution: very strong، strong، moderate، weak، and very weak. SUDI is applied to10 stopes in different parts of Venarch Manganese Mines (Qom، Iran). In this way، a semi-automatic cavity monitoring system is implemented in the stopes. The regression analysis method shows that there is a relationship between SUDI and the actual unplanned dilution in equivalent linear overbreak/slough with a correlation coefficient (R2 = 0.8957).

The permeability and coupled behavior of pore pressure and deformations play an important role in hydraulic fracturing (HF) modeling. In this work، a poroelastic displacement discontinuity method is used to study the permeability effect on the HF development in various formation permeabilities. The numerical method is verified by the existing analytical and experimental data. Then the propagation of a hydraulic fracture in a formation with a range of permeabilities is studied. The time required for propagation of an HF to 10 times its initial length is used to compare the propagation velocity in the formations with different permeabilities. The results obtained show that the HF propagation can be significantly delayed by a permeability less than almost 10-9 D. Also the effect of HF spacing on the propagation path is studied. It was shown that the stress shadowing effect of HFs remained for a longer spacing than in the elastic model due to the required time for fluid leak-off in the formation. Also the propagation angles are higher in the poroelastic model predictions than the elastic model. Therefore، it is proposed to use the poroelastic model when studying multi-HF propagation in order to avoid errors caused by neglecting the pore fluid effects on the HF propagation paths.

The extraction behavior of Cu(II) ions from a real sulfate liquor obtained from the heap leaching stage of a copper oxide ore was investigated using a chelating reagent، Chemorex CP-150 in kerosene. A comparative study was also carried out on the extraction capability of Cu(II) ions using other solvents including D2EHPA and Cyanex 272.Chemorex CP-150 demonstrated an effective and selective extraction performance of copper with the amount of extracted Fe less than 15%. Also the results obtained indicated that more than 66.4% and 96.99% of Cu were transferred to the organic phase in a single extraction stage using 15% (v/v) Chemorex CP-150 at the A:O phase ratios of 1:1 and 1:4، respectively. In addition، the McCabe-Thiele diagram exhibited that two extraction stages were required to achieve the maximum amount of Cu at a 1:1 phase ratio under the optimal conditions (25 °C، pH 2.5، and 20 min contact time). Also، thermodynamic data proved that the extraction process was slightly endothermic (ΔH = 7.62 kJ/mol)، indicating the relatively smaller heat effects on the formation of a single complex species (CuR2). Stripping of copper from the loaded organic phase was also conducted، and it was found that ~99.38% copper could be recovered using 165 g/L H2SO4 at a 2:1 A:O phase ratio after 5 minutes stripping.

The study area، located in the southern section of the Central Iranian volcano–sedimentary complex، contains a large number of mineral deposits and occurrences which is currently facing a shortage of resources. Therefore، the prospecting potential areas in the deeper and peripheral spaces has become a high priority in this region. Different direct and indirect methods try to predict promising areas for future explorations، most of which are very time-consuming and costly. The main goal of mineral prospecting is applying a transparent and robust approach for identifying high potential areas to be explored further in the future. This work presents the procedure taken to create two different Cu-mineralization prospectivity maps. The first map is created using a knowledge-driven fuzzy technique and the second one by a data-driven Artificial Neural Network (ANN) approach. In this study aim is to investigate the results of applying the ANN technique and to compare them with the outputs of applying the fuzzy logic method. The geo-datasets employed for creating evidential maps of porphyry Cu mineralization include the solid geology map، alteration map، faults، dykes، airborne total magnetic intensity، airborne gamma-ray spectrometry data (U، Th، K and total count)، and known Cu occurrences. Based on this study، the ANN technique is a better predictor of Cu mineralization compared to the fuzzy logic method. The ANN technique، due to capabilities such as classification، pattern matching، optimization، and prediction، is useful in identifying the anomalies associated with the Cu mineralization.

Slope stability analysis is one of the most important problems in mining and geotechnical engineering. Ignoring the importance of these problems can lead to significant losses. Selecting an appropriate method to analyze the slope stability requires a proper understanding of how different factors influence the outputs of the analyses. This paper evaluates the effects of considering the real geometry، changes in the mesh size، and steepness of the slope، as the dimensional effects، and changes in the geomechanical parameters، as the media effects on the global slope stability of an open-pit mine using finite difference methods with a strength reduction technique. The case study is the Tectonic Block I in the old pit (steep slope) and the redesigned new pit (gentle slope) of the Choghart iron mine. In the first step، a series of 2D and 3D slope stability analyses are performed and compared in terms of safety and potential failure surface. The results obtained show that by considering the real geometry of the slope، the FOS3D/FOS2D ratio (3D-effect) is more than 1 in the all cases. The 3D-effect in the new pit is smaller than that in the old one. In the next step، sensitivity analysis of the cohesion and the friction angle is performed for the 2D and 3D analyses. The results obtained show that the sensitivity of the analyses in terms of the 3D-effect to the change in the friction angle، especially in a low-friction angle، is more significant than that to the change in the cohesion.

The dynamic response of slopes against earthquake is commonly characterized by the earthquake-induced displacement of slope (EIDS). The EIDS value is a function of several variables such as the material properties، slope geometry، and earthquake acceleration. This work is aimed at the prediction of EIDS using the Monte Carlo simulation method (MCSM). Hence، the parameters height، unit specific weight، cohesion، friction angle، vibration duration، and maximum horizontal acceleration are used to predict the EIDS values. To do this، a multiple non-linear regression relationship is first derived between EIDS and the independent variables. Then MCSM is performed based on the developed regression equation. The results obtained demonstrate that the stochastic approach used is able to successfully reproduce the EIDS values and calculate the confidence intervals. The average of the measured and simulated values for EIDS was 4.34 cm and 4.48 cm، respectively. Eventually، the results of a performed correlation sensitivity analysis revealed that the maximum horizontal acceleration had the greatest impact on EIDS.

The purpose of this work is to compare the linear and non-linear kriging methods in the mineral resource estimation of the Qolqoleh gold deposit in Saqqez، NW Iran. Considering the fact that the gold distribution is positively skewed and has a significant difference with a normal curve، a geostatistical estimation is complicated in these cases. Linear kriging، as a resource estimation method، can be problematic and gives an unrealistic gold grade. In order to check and correct the errors in the linear methods، the non-linear kriging method has been deployed. One of the applicant's non-linear estimation methods is Indicator Kriging (IK). The IK method converts grade values into binary units of 0 and 1 using multiple thresholds that can be selected by the number-size (N-S) fractal model. The N-S model identifies important and critical thresholds based on the grade distribution. In IK، the Multiple Indicator Kriging (Multiple IK) and Median Indicator Kriging (Median IK) methods could be involved due to the number of indicator thresholds. IK is not sensitive to high values. Here، we make a comparison between Median IK and Multiple IK as well as those with ordinary kriging (OK)، which is a linear kriging method. Overall، we conclude that all of these methods are suitable for resource estimation among these methods، although the IK method is better for estimation in different categories of gold grades.

This research was performed with the objective of evaluating the accuracy of spectral angle mapper (SAM) classification using different reference spectra. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital images were applied in the SAM classification in order to map the distribution of hydrothermally altered rocks in the Kerman Cenozoic magmatic arc (KCMA)، Iran. The study area comprises main porphyry copper deposits such as Meiduk and Chahfiroozeh. Collecting reference spectra was considered after pre-processing of ASTER VNIR/SWIR images. Three types of reference spectra including image، USGS library، and field samples spectra were used in the SAM algorithm. Ground truthing and laboratory studies including thin section studies، XRD analysis، and VNIR-SWIR reflectance spectroscopy were utilized to verify the results. The accuracy of SAM classification was numerically calculated using a confusion matrix. The best accuracy of 74.01% and a kappa coefficient of 0.65 were achieved using the SAM method using field samples spectra as the reference. The SAM results were also validated with the mixture tuned matched filtering (MTMF) method. Field investigations showed that more than 90% of the known copper mineralization occurred within the enhanced alteration areas.

Fracture mechanics is a vital component involved in studying the exact behavior of rock materials. Detection and assessment of the behavior of rock joints injected by grout plays an important role in numerical modelling in rock mechanic projects. The importance of mechanisms associated with initiation and propagation of cracks due to hydraulic fracturing has led to a considerable interest in investigation and analysis of this phenomenon. In this work، the process of propagation of cracks on the wall of boreholes، drilled in single and bi-material structures، was simulated in ABAQUS software employing the extended finite element method. The energy method was implemented to obtain the stress intensity factor and energy release rate through applying J integral around the crack tip. The method was applied to two rock types، diorite and granite at the Chadormalu iron mine located in the central part of Iran. It was concluded that assuming the same geometry، the possibility of crack propagation at the boundary between two materials was more than the single material medium. Therefore، in dealing with a bi-material medium، if the purpose is to measure the in situ stresses، the measurement should not be performed on the boundary between the two materials.

In this work، adsorption of the potassium amyl xanthate collector on the pure chalcopyrite surface was studied by applying atomic force microscopy (AFM). The adsorption experiments were carried out at different concentrations of the collector and at diverse pH values in the presence or absence of exterior ions. The changes occurring in the surface morphology of chalcopyrite due to the collector adsorption were evaluated by measuring the contact angle of the collector and its surface coating. According to the 3D images obtained by AFM، an increase in the pH value from 7.5 to 9.5 at two concentrations of 25*10-3 and 50*10-3 g/ton of the collector would increase the number of particles adsorbed on the surface، improve the adsorption morphology، and reduce the contact angle. Moreover، at a constant pH value، increasing the collector would result in the proliferation of contact angles as well as a relative increase in the number of particles. By comparing the morphological surface changes in the tap and distilled water samples، applying tap water، owing to the presence of Cu2+ ions and activation of the surface through the production of CuS، the quality and quantity of adsorption would be increased. The use of tap water not only can account for an appropriate coating by the collector but also causes to reduce the consumption of collector for at least 50%.

A lead-zinc carbonate ore sample containing 2.5% Pb and 9.39% Zn was used in this research work. The sample was prepared from the Darreh-Zanjir mine located in the Yazd province (Iran). Influences of the influential factors on flotation of smithsonite and cerussite were investigated. Among the different parameters involved، dosages of the dispersant، depressants، sulfidizing agent، and collectors de-sliming prior to lead or zinc flotation were essential for the effective recovery and grade of the Zn and Pb flotation concentrates. In addition، the anionic، cationic، and mixed (cationic/anionic) collectors were employed for flotation of smithsonite. The results of reverse and cumulative flotation of both Zn and Pb were relatively low in comparison with the direct process without depressant. Flotation of smithsonite using mixed collectors (Armac C+KAX) showed promising results. Also dosages of chemicals in the cleaning stage for the Zn and Pb concentrates were optimized، and finally، after the cleaner stage for both lead and zinc، a cerussite concentrate with Pb grade and recovery of 49.82% and 60.06%، respectively، and smithsonite concentrate with Zn grade and recovery of 35.47% and 68.56%، respectively، were obtained under the optimal conditions. Furthermore، kinetics of Zn and Pb oxide mineral flotations in the rougher and cleaner stages were studied، which showed that some kinetics models، especially the classical first-order model، could predict the flotation behaviour of the Zn and Pb oxide minerals.

Flotation is a common process in sulfide ore beneficiation. Due to the restrictions and lack of access to high-quality water sources for industrial purposes، recycled water plays an important role in the flotation processes. Due to the existence of various organic and inorganic substances in the process، water influences the flotation performance. In this work، the effect of accumulation of sulfate ion in processed water on galena flotation was investigated. Flotation experiments using processed water without sulfate ion led to a concentrate containing 40.7% of lead and a maximum recovery of 58.9%. The presence of higher sulfate ion levels (2000 M) in processed water caused a significant decrease in the grade and recovery of the lead concentrate. With 2000 mg/L of sulfate ion، the grade and recovery of lead decreased from 40.7 to 24.3% and from 58.9 to 32.1 %، respectively. Thermodynamic calculations showed that when the sulfate ion concentration was increased from 300 to 2000 ppm، it was more likely that lead sulfate (solid) was formed. With increase in the xanthate ion concentration from 10-6 to 10-4 M، could be substituted by . On the basis of the results obtained، it was concluded that in order to reduce the negative effects of sulfate ion accumulation in water and increase the efficiency of the galena flotation process، higher dosages of xanthates should be added to the system.

This paper describes a preliminary study of the adsorption of toxic elements from synthetic wastewater in a batch mode. Clay minerals have been highly considered as inexpensive available adsorbents that adapt with the environment due to a special level and a high potential of adsorption. In the present research work،low-cost natural minerals of speiolite from the Iliato mine (located in NE Iran) and zeolite from the Aftar mine (located in north of Iran) are used to remove nickel(II)، antimony(III)، and arsenic(V) from synthetic wastewater. The adsorption experiments are conducted by varying the initial concentrations of the elements، pH values، adsorption times، and adsorbent dosage. The experimental isotherm data is analyzed using the Langmuir and Freundlich equations. Concerning a higher Langmuir coefficient R2 in nickel and antimony، the mechanism of adsorption of these elements is mono-layer and homogenous. Based on the Freundlich model، adsorption of arsenic is multi-layer and heterogeneous. The kinetic studies show that the Ni، Sb، and As adsorption mechanism is well-described by a pseudo-second-order kinetic model. The thermodynamic parameters indicate that the adsorption process has an exothermic character and is more feasible with decreasing temperature. Based on the experimental results، it can be concluded that natural sepiolite and zeolite has the potential of application as an efficient adsorbent for the removal of toxic elements from synthetic wastewater.